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Comcast Business Gateway - multiple static IPs

Posted on 2008-10-14
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Last Modified: 2013-12-14
I have a block of five static IPs from Comcast. On one, I have configured my firewall with a web server behind that NATed and port forwarded. This works fine. I would like to add another server that is not behind the firewall. I added  the second static IP to the server, cabled it to the second port on the CBG.
I can ping and telnet to the server with the second static ip  from my LAN with no problem. I cannot do either from the Internet.

Any ideas? Thanks, mike morgan
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Question by:michaelwmorgan
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by:debuggerau
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Are you sure that the firewall is not portforwarding/natting that IP already?

Do you have the firewall config to check it? What about the router natting? Is that enabled too?

I'd start with a simple network map, showing the devices and ports, ip addresses and devices... (happy to use pseudo ones for your protection, but try and keep the internal consistent)

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by:michaelwmorgan
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Thanks for responding. I've attached a simple diagram. The strange thing is, attaching a firewall, natting and port forwarding to my web/exchange server, all that works fine. Simply attaching a second server to the SMC and assigning a second static IP is not working.
netwrk.jpg
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by:michaelwmorgan
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Small mistake in diagram Server 1 should read NAT 70.91.72.x1
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debuggerau earned 500 total points
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could be a few things, but firstly I'd check you have the right network mask, its a /29, so the mask should be 255.255.255.248
Also, ensure your default gateway is the external address of the SMC...
From then, I'd want to ensure that the static IP's are actually active on the SMC, maybe trying that IP address on the firewall to check its working might be the simplest way, unless you can get access, but I though these were configured from comcast? Else post the config..
Comcast can also check from their end cant they?
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by:michaelwmorgan
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I should have included the netmasks in the diagram. They are indeed 255.255.255.248 on all the 70.91.72.x nodes. GW on Server 2 is the external addr of the SMC. Actually you can get accessto the router/modem/firewall/piece of junk, however it's via a rather limited web gui. I want to avoid the dreaded tech support call to Comcast, but it's looking like that maybe the only way. There are a couple of other questions on EE that refer to similar configs, but I can't make sense of the solutions, because they point to things I have already tried or verified.
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by:michaelwmorgan
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I broke down and called Comcast. It turned out the Firewall in the CBG router was no turned off for all the static ips. IT was blocking the ports I was trying to use. Thanks for all your sugestions.
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Author Closing Comment

by:michaelwmorgan
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I took your advice and contacted the vendor, which proved to be the solution. THanks
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